CXCL12 and chronic myelogenous leukemia, BCR-ABL1 positive: Drastic changes in the BM sinusoidal vasculature structure, increased microvascular density in CML patients. CXCL12 inhibits LSC expansion and maintains quiescence of TKI‐resistant LSCs in CML. CXCL12 depletion from MSCs enhances TKI efficacy. CXCL12‐expressing MSCs are key for preserving TKI‐resistant LSCs.